Ruby SHGetFolderPath - different implementations

shgetfolderpath.rb

require 'fiddle/import'
require 'fiddle/types'

module Win32FiddleDirectories
  extend Fiddle::Importer
  include Fiddle::Win32Types # adds HWND, HANDLE, DWORD type aliases
  
  # calling this appears to hose everything up!
  # dlload "shell32", "kernel32"

  typealias 'LPWSTR', 'wchar_t*'
  typealias 'LONG', 'long'
  typealias 'HRESULT','LONG'

  # https://msdn.microsoft.com/en-us/library/windows/desktop/aa383751(v=vs.85).aspx
  # HRESULT SHGetFolderPath(
  #   _In_  HWND   hwndOwner,
  #   _In_  int    nFolder,
  #   _In_  HANDLE hToken,
  #   _In_  DWORD  dwFlags,
  #   _Out_ LPTSTR pszPath
  # );
  extern 'HRESULT SHGetFolderPath(HWND, int, HANDLE, DWORD, LPWSTR)'

  PROGRAM_FILES = 0x0026
  COMMON_APPDATA = 0x0023

  def self.get_program_files
    buffer = 0.chr * 1024
    SHGetFolderPath(0, PROGRAM_FILES, 0, 0, buffer)
    buffer.strip
  end

  def self.get_common_appdata
    buffer = 0.chr * 1024
    SHGetFolderPath(0, COMMON_APPDATA, 0, 0, buffer)
    buffer.strip
  end
end

module Win32Directories  
  require 'Win32API'

  PROGRAM_FILES = 0x0026
  COMMON_APPDATA = 0x0023

  # https://msdn.microsoft.com/en-us/library/windows/desktop/aa383751(v=vs.85).aspx
  # HRESULT SHGetFolderPath(
  #   _In_  HWND   hwndOwner,
  #   _In_  int    nFolder,
  #   _In_  HANDLE hToken,
  #   _In_  DWORD  dwFlags,
  #   _Out_ LPTSTR pszPath
  # );
  # L - 32-bit unsigned
  # P - point to a struct / null-terminated string
  # HWND, int (32-bit integer), HANDLE, DWORD, LPWSTR / HRESULT return value
  SHGetFolderPath = Win32API.new('shell32', 'SHGetFolderPath', ['P','L','P','L','P'], 'L')
  
  def self.get_program_files
    buffer = 0.chr * 1024
    SHGetFolderPath.call(0, PROGRAM_FILES, 0, 0, buffer)
    buffer.strip
  end

  def self.get_common_appdata
    buffer = 0.chr * 1024
    SHGetFolderPath.call(0, COMMON_APPDATA, 0, 0, buffer)
    buffer.strip
  end
end